Diabetes currently affects 246 million people worldwide and is expected to affect 380 million by 2025 (International Diabetes Federation statistic as of Nov. 15, 2007). Type 2 diabetes constitutes about 85% to 95% of all diabetes cases in developed countries and accounts for an even higher percentage in developing countries. The epidemic nature of diabetes continues to affect ever-increasing numbers of people around the world while public awareness remains low.
Diabetes is any disorder characterized by excessive urine excretion. The most common form of diabetes is diabetes mellitus, a metabolic disorder in which there is an inability to oxidize carbohydrate due to disturbances in insulin function. Diabetes mellitus is characterized by elevated glucose in the plasma and episodic ketoacidosis. Additional symptoms of diabetes mellitus include excessive thirst, glucosuria, polyuria, lipemia and hunger. If left untreated the disease can lead to fatal ketoacidosis. Other forms of diabetes include diabetes insipidus and brittle diabetes. Diabetes insipidus is the result of a deficiency of antidiuretic hormone. The major symptom of diabetes insipidus (excessive urine output) results from an inability of the kidneys to resorb water. Brittle diabetes is a form that is very difficult to control. It is characterized by unexplained oscillations between hypoglycemia and acidosis.
Criteria, which clinically establish an individual as suffering from diabetes mellitus, include: (1) having a fasting plasma glucose level in excess of 126 mg/dL (7 mmol/L). Normal levels should be less than 100 mg/dL (5.6 mmol/L) or (2) having plasma glucose levels in excess of 200 mg/dL (11 mmol/L) at two times points during an oral glucose tolerance test, OGTT, one of which must be within 2 hrs of ingestion of glucose.
The earlier a person is diagnosed with diabetes the better chance the person has of staving off the primary negative consequences which are renal failure, blindness and limb amputations due to circulatory problems. The American Diabetes Association has discussed recommending that physicians consider patients to be pre-diabetic if their fasting blood glucose level is above 100 mg/dL but less than 125 mg/dL and whose glucose levels are at least 140 mg/dL but less than 200 mg/dL following an oral glucose tolerance test (OGTT).
Diabetes mellitus is a heterogeneous clinical disorder with numerous causes. Two main classifications of diabetes mellitus exist, idiopathic and secondary. Idiopathic diabetes is divided into two main types; insulin dependent and non-insulin-dependent. Insulin-dependent diabetes mellitus, IDDM (more commonly referred to as type 1 diabetes) is defined by the development of ketoacidosis in the absence of insulin therapy. Type 1 diabetes most often manifests in childhood (hence also called juvenile onset diabetes) and is the result of an autoimmune destruction of the b-cells of the pancreas. Non-insulin-dependent diabetes mellitus, NIDDM (more commonly referred to as type 2 diabetes) is characterized by persistent hyperglycemia but rarely leads to ketoacidosis. Type 2 diabetes generally manifests after age 40 and therefore has the obsolete name of adult onset-type diabetes. Type 2 diabetes can result from genetics defects that cause both insulin resistance and insulin deficiency. There are two main forms of type 2 diabetes: (1) late onset associated with obesity; and (2) late onset not associated with obesity. Many, if not all, of the negative long term effects of living with type 2 diabetes are due to persistent hyperglycemia. For this reason a major goal of therapeutic intervention in type 2 diabetes is to reduce circulating glucose levels.
The major function of insulin is to counter the concerted action of a number of hyperglycemia-generating hormones and to maintain low blood glucose levels. Because there are numerous hyperglycemic hormones, untreated disorders associated with insulin generally lead to severe hyperglycemia and shortened life span.
In addition to its role in regulating glucose metabolism, insulin stimulates lipogenesis, diminishes lipolysis, and increases amino acid transport into cells. Insulin also modulates transcription, altering the cell content of numerous mRNAs. It stimulates growth, DNA synthesis, and cell replication, effects that it holds in common with the insulin-like growth factors (IGFs) and relaxin.